Method and stamp for repeatable image correlation micro patterning and resulting specimen produced therefrom

Abstract

A method and surface micro patterned stamp for patterning image correlation test specimens is disclosed. The stamp may be formed and applied to the surface of structural components and laboratory test specimens in a repeatable fashion while reducing requisite infrastructure and time. The resulting test specimen incorporating the surface micro stamped pattern is also disclosed.

We claim: 
     
       1. A method of patterning image correlation specimens comprising the steps of:
 providing a surface micro patterned stamp having a designated pattern thereon, wherein the designated pattern includes microfeatures; 
 providing a specimen; 
 depositing a patterning material onto the specimen; 
 engaging the surface micro patterned stamp with the specimen so that the patterning material replicates the designated pattern on the specimen, wherein patterning material is consistently not transferred onto the specimen between microfeatures of the designated pattern of the surface micro patterned stamp; 
 allowing the patterning material to cure; 
 removing the surface micro patterned stamp from the specimen to form an image correlation specimen; and 
 measuring surface strain of the image correlation specimen. 
 
     
     
       2. The method of  claim 1  further comprising the step of depositing the patterning material onto the surface micro patterned stamp prior to depositing the patterning material onto the specimen. 
     
     
       3. The method of  claim 1  further comprising the step of applying an alternate patterning material to the specimen after the first patterning material has cured. 
     
     
       4. The method of  claim 3  wherein the alternate patterning material is a distinct color from patterning material. 
     
     
       5. The method of  claim 1  further comprising the step of fabricating a surface micro patterned stamp. 
     
     
       6. The method of  claim 5  wherein the surface micro patterned stamp is fabricated by casting or molding the surface micro patterned stamp from a stamp master. 
     
     
       7. The method of  claim 6  further comprising the step of patterning electron beam resist on a prototype using electron beam lithography to fabricate the stamp master. 
     
     
       8. The method of  claim 1  wherein the surface micro patterned stamp is flexible. 
     
     
       9. The method of  claim 1  wherein the surface micro patterned stamp is a roller shaped stamp. 
     
     
       10. The method of  claim 1  wherein the surface micro patterned stamp is composed of a polymer material. 
     
     
       11. The method of  claim 10  wherein the polymer material is selected from the group consisting of silicone rubber, styrenic block copolymer rubber, ethylene propylene diene monomer rubber, and urethane rubber. 
     
     
       12. The method of  claim 1  wherein the specimen is curved. 
     
     
       13. The method of  claim 1  wherein the specimen is flat. 
     
     
       14. The method of  claim 1  wherein the patterning material is opaque. 
     
     
       15. The method of  claim 1  wherein the patterning material is transparent. 
     
     
       16. The method of  claim 1  wherein the patterning material is ink. 
     
     
       17. The method of  claim 16  wherein the ink is selected from the group consisting of photoresist, electron beam resist, paint, and dye. 
     
     
       18. A method of patterning image correlation specimens comprising the steps of:
 providing a substrate; 
 patterning a resist on the substrate to create a template having a designated pattern having microfeatures on the template; 
 casting a microstructured stamp from the template, wherein the microstructured stamp comprises a negative of the designated pattern having microfeatures; 
 providing a specimen; 
 depositing pattern material onto the specimen; 
 engaging the microstructured stamp with the specimen so that the pattern material forms the designated pattern having microfeatures on the specimen and wherein pattern material is consistently not transferred onto the specimen between microfeatures of the designated pattern; 
 curing the pattern material onto the specimen to form a test specimen suitable for image correlation testing; 
 removing the microstructured stamp from the specimen; and 
 measuring surface strain of the image correlation specimen. 
 
     
     
       19. The method of  claim 18  wherein the stamp is composed of rubber. 
     
     
       20. The method of  claim 19  wherein the rubber is silicone rubber. 
     
     
       21. The method of  claim 20  further comprising the step of treating the microstructured stamp with an oxygen plasma. 
     
     
       22. The method of  claim 18  wherein the substrate is selected from an aluminum prototype or a silicon prototype. 
     
     
       23. The method of  claim 18  wherein the resist is electron beam resist that is patterned on the substrate using electron beam lithography. 
     
     
       24. The method of  claim 18  wherein the resist is photoresist that is patterned on the substrate using photolithography. 
     
     
       25. The method of  claim 18  further comprising the step of depositing the pattern material on the microstructured stamp prior to depositing the pattern material onto the specimen. 
     
     
       26. The method of  claim 18  wherein the pattern material is opaque and the designated pattern having microfeatures formed on the specimen is an opaque micro pattern. 
     
     
       27. A method of patterning image correlation specimens comprising the steps of:
 providing a substrate; 
 patterning a resist on the substrate to create a template having a designated pattern having microfeatures; 
 casting a silicone rubber from the template, wherein the silicone rubber comprises a negative of the designated pattern having microfeatures; 
 casting a urethane rubber from the silicone rubber, wherein the urethane rubber comprises the designated pattern having microfeatures; 
 applying pattern material onto the urethane rubber; 
 providing a specimen; 
 engaging the urethane rubber with the specimen so that the pattern material contacts the specimen, wherein pattern material is consistently not transferred onto the specimen between microfeatures of the designated pattern of the urethane rubber; 
 curing the pattern material onto the specimen to form a test specimen suitable for image correlation testing; 
 removing the microstructured stamp from the specimen; and 
 measuring surface strain of the image correlation specimen. 
 
     
     
       28. The method of  claim 27  wherein the pattern material is opaque and the designated pattern having microfeatures formed on the specimen is an opaque micro pattern.